11. Use a Signature

You're helped if your e-mail contains an e-mail signature -- since so many spam messages don't.

Short signature present (no empty lines)
-0.30

Short signature present (empty lines)
-2.09

Long signature present (no empty lines)
-3.13

Long signature present (empty lines)
-0.30

Contains what looks like an 'E-Mail Disclaimer'
-0.70

Contains what looks like an email attribution
-1.63

Contains what looks like a quoted email text
-0.83

12. Don't Mention Spam Law Compliance

It's very unwise to claim that you observe all the spam laws. Only spammers say that. SpamAssassin will assess you from .91 to 3.47 points for this. If you mention House Bill 4176 you'll be fined 2.02 points. H.R. 3113 dings you 2.93.

13. Message Size of 20K to 40K Helps

Since so many spam messages are under 20K, SpamAssassin gives you credit for a message size between 20K and 40K (-.71). Over 40K helps you less (-.12).

14. Remove Spam Flag Addresses from Your List

Occasionally, evil-minded people will add e-mail addresses to your list just to get you in trouble with the anti-spammers. Try scanning your e-mail database for an e-mail address that starts with abuse@, postmaster@, or nospam@. Sometimes an e-mail address will be inserted that subscribes you to an autoresponder each time you send out an e-mailing. You might scan for the word "subscribe" among your e-mail addresses (though this one won't affect you with the spam filters).

15. Monitor Your "From" E-mail Address for Challenge Systems

I am seeing a small but increasing number of recipients who use systems that block all e-mails except those that take the trouble to respond to an e-mail message, and perhaps give a name and reason for the e-mail. Thus, it's important to monitor the mailbox for your "From" e-mail address to catch these.